Triplet repeat expansions of specific DNA loci have recently been shown to underlie ten neurological disorders, including Huntington's disease, fragile X syndrome, and myotonic dystrophy, and are suspected to be involved in several more. Polymerase chain reaction (PCR) based analysis of the number of repeats provides diagnostic information. There is a need to develop methodologies for automated, high- throughput DNA analysis for genetic typing of disease markers and for linkage analysis of undiscovered genes. This proposal describes development of integrated reagents and procedures to perform di-, tri-, and tetra-nucleotide repeat size typing of fluorescent PCR fragments by capillary array electrophoresis. The goal of Phase I is to optimize multiplex genetic typing protocols for a 96-capillary system and demonstrate typing of CA- repeat polymorphisms with 1,800 samples from families affected with hemochromatosis. The integrated methods, instrument, and software will have the capacity to analyze up to 5.5 million genotypes per year, increasing throughput by a factor of nine over current systems. The goals of Phase II are to validate the capillary array genetic analysis system for typing of Huntington's disease, fragile X syndrome and myotonic dystrophy, and test a proposed genotype-phenotype correlation of multiple sclerosis progression with repeat polymorphisms in the control region of the myelin basic protein gene.